Analysis of the Collaborative Perinatal Project (CPP) data continues in the area of maternal infection. (The CPP is a prospective study of approximately 60,000 gravidae and the follow-up of their children through the seventh year of life.) The relationship of maternal infection during pregnancy with the later status of the child is being examined using both clinical and serologically-confirmed infections in the mother. Two primary methodologies have been used, a prospective and a case control approach. A prospective assessment of risk of specified childhood outcome was used for all clinically confirmed infections. Since serological confirmation of all of the common infections occurring during pregnancy on all women in the project would not have been feasible, a case control design has been implemented assessing the titer of 11 antigens in women with abnormal children, in comparison with matched control women with normal children. Special studies of specific infections such as condylomata and toxoplasmosis are in progress or have been completed and a descriptive study of the distribution of titers and frequency of seroconversions by race and age of gravidae for various antigens in a population of pregnant women has been completed. The prospective serological study of toxoplasmosis and its relationship with pregnancy outcome, based on the first 23,000 pregnancies in the study, has shown increases in the risk of deafness, microcephaly and low IQ among children born to women with high maternal antibody to toxoplasmosis.